1. Field of the Disclosure
This disclosure relates to an electrophoresis display device capable of preventing a sensing error and reducing power consumption.
2. Description of the Related Art
Recently, display devices which can display newspapers and journals have been widely researched. An electrophoresis display device is among the display devices used for newspapers or journals. The electrophoresis display device drives electrified (or charged) corpuscles and then displays an image. In other words, the electrophoresis display device displays an image using electrophoresis.
An electrophoresis display device unified with a sensor has been recently proposed, as shown in FIGS. 1 and 2. FIG. 1 is a circuitry diagram showing an electrophoresis display device of the related art, and FIG. 2 is a cross-sectional view showing the structure of an electrophoresis display device of the related art.
As shown in FIG. 1, an electrophoresis display device includes gate lines 101 and data lines 103 arranged to cross each other on a thin film transistor array substrate. The gate lines 101 and the data lines 103 crossing each other define pixel regions. Each pixel region includes a thin film transistor 112, a sensor 114, and an output transistor 116.
The thin film transistor 112 is connected to the respective gate line 101, the respective data line 103, and a respective pixel electrode. Such a thin film transistor 112 is activated by a gate signal applied from the respective gate line 101. It then supplies the respective pixel electrode with a data voltage applied from the respective data line 103.
The pixel electrode overlaps a previous gate line to form a storage capacitor Cst. An ink layer of an ink film forms an electrophorectic capacitor Cep due to a signal. The data voltage applied to the pixel electrode is charged into the storage capacitor Cst.
The sensor 114 is connected to an off-voltage line 105 and a power supply line 107. The off-voltage line 105 always receives an off-voltage. The power supply line 107 always receives a supply voltage. The sensor 114 is driven to generate a sensing signal of a fixed level.
The output transistor 116 is connected to a respective output control line 109, a respective read-out line 110, and the respective sensor 114. The output control line 109 always receives an output control signal. Accordingly, the output transistor 116 is turned on (activated) by the output control signal. It then applies the sensing signal from the respective sensor 114 to the respective read-out line 110.
A sensing signal capacitor C is provided between gate and drain electrodes of the sensor 114. The sensing signal capacitor C charges the sensing signal generated in the sensor 114.
Referring to FIG. 2, the electrophoresis display device of the related art includes a thin film transistor array substrate 120 and an ink film 130. The thin film transistor array substrate 120 includes thin film transistors 112, pixel electrodes 124, sensors 114, and output transistors 116 arranged on a substrate 122. The ink film 130 includes a common electrode 134 formed on a base film 132 as well as the ink layer 136 formed on the common electrode 134.
The related art electrophoresis display device with the above configuration forces the sensing signal of the fixed level generated in the sensor 114 to always be output through the output transistor 116. If the electrophoresis display device is touched by a human finger, the finger blocks light from entering into a portion of the electrophoresis display device. Therefore the sensing signal generated in the sensor 114 is varied. The varied sensing signal is output through the output transistor 116. Accordingly, a detector (not shown) connected to the read-out line 110 monitors the variation of the sensing signal when the device is touched or not touched. This detector then determines whether or not the electrophoresis display device is being touched.
However, the related art display device misidentifies a touch when light incident to the sensor 114 is shielded but the sensor is not actually being touched. More specifically, even though a human finger is only positioned above the ink film 130 but does not touch it, light is prevented from entering into the sensor 114, thereby generating an error which allows the detector to wrongly identify the touch of human finger. In other words, whenever light is shielded by any object, not merely human finger, the related art electrophoresis display device identifies a touch regardless of whether or not the device is actually being touched.
In addition, the related art electrophoresis display device always applies the output control signal to the gate electrode of the output transistor 116 in case the touch function is not used. Accordingly, electric power consumption is increased in the related art electrophoresis display device.